A nonchalant Elon Musk met with reporters on Friday evening. “It didn't put a hole in the ship or fall over, so we're pretty excited,” the SpaceX founder said at a news conference.

This is what understatement sounds like. Musk's Falcon 9 rocket had just shot 200km up into space and flown almost horizontal to the planet at six times the speed of sound, before falling back to Earth. Then, somehow, it landed like a feather on a robotic barge in the ocean. The Falcon even found time to put an inflatable space habitat into orbit, too.

“This was a beautiful day, and circumstances were good," Musk continued. "It's quite a tiny target. It's really trying to land on a postage stamp out there.”

Engines and boosters have been dropping into the big drink from the moment NASA began launching Mercury astronauts into space. Most of those rockets sunk to the bottom of the ocean. Some components of the space shuttle were recovered, of course, and the orbiter itself landed on a runway. But never before Friday has a rocket blasted into space and then returned to make a vertical landing at sea.

These are heady times for a new generation of private spaceflight companies. It was only five months ago that Blue Origin launched its New Shepard rocket to space before landing it vertically in West Texas. SpaceX followed suit in December when its larger and more powerful Falcon 9 not only flew to space, but delivered a satellite into orbit and touched down at a landing site along the Florida coast near its launch pad. Now SpaceX has taken the significant step of landing at sea.

How do you launch and land a rocket in the same day? Here's how.

SpaceX

A couple of weeks ago the primary payload, the Bigelow Expandable Activity Module, was loaded into the trunk of the Dragon spacecraft.

SpaceX

The day before launch, Dragon was loaded with "late load" cargo in advance of the April 8 trip to the International Space Station.

SpaceX

And then the Falcon 9 was ready to go.

NASA

The Dragon spacecraft wrapped up tight.

SpaceX

The instantaneous launch window meant the Falcon 9 had to go right on time.

NASA

The perfect day for a launch - hardly a cloud in the sky.

NASA

And there it goes.

The Falcon 9's nine engines burn with a thrust of more than 1.5 million pounds.

NASA

Before the landing Elon Musk tweeted out this photo from the autonomous drone ship.

That’s critical, because it's much more fuel efficient for a rocket to touchdown on a ship below the point where it releases its payload into orbit, rather than go all the way back to a landing site near the Florida coast. SpaceX estimates that only one-half of its launches will have enough fuel to fly back to the coast after fulfilling their primary missions.

After trying reusability with the space shuttle, which proved far more expensive to refurbish for subsequent flights, NASA has largely given up on reusable spaceflight. Russia, Europe, and other government agencies have too. So it fell to the new space companies—with their ethos of low-cost, frequent launches as a means of opening up access to space—to push the technology forward.

SpaceX and Blue Origin have been the most visible proponents of reusable launch vehicles. But other firms, including XCOR, Masten Space Systems, and Virgin Galactic, are interested too. They do not seek so much to win lucrative government contracts, but to get lots of people and stuff into space, to create a space economy, and to set about the business of colonizing the solar system. “This was a really good milestone for the future of spaceflight,” Musk said. “This is another step to the stars.”

Further Reading

Despite SpaceX’s arresting success on Friday the job is not yet done. The venerable space shuttle offers a sobering lesson for these new space companies. Whereas NASA said in the 1970s the shuttle would slash the cost of delivering payloads into space to $25 a pound, it ended up costing closer to $25,000 a pound. It's one thing to land a rocket, and it's another thing to fly it again without spending a lot of time and money.

Blue Origin has flown the same single-engine New Shepard propulsion module and spacecraft three times in a little more than four months. Refurbishment costs have been in the low tens of thousands of dollars. The company’s founder, Jeff Bezos, believes his technology will scale to a much larger orbital vehicle, but that remains to be proven.

So too must Musk prove that his Falcon 9 rocket can be re-flown with modest modifications. After the first SpaceX landing in December, the company performed a static firing test of the vehicle, which went well until one of the nine engines showed thrust fluctuations. That rocket will stand as a monument outside the company’s headquarters in Hawthorne, Calif. Perhaps the Falcon 9 that landed at sea will be flown again.

“I think that's likely,” Musk said Friday. SpaceX will try to return the booster back to Cape Canaveral, in Florida, by Sunday. After running a series of tests on the Falcon, the company plans to fire its engines 10 times in a row on the ground. “If things look good it will be qualified for reuse,” Musk said. “We’re hoping to relaunch it on an orbital mission, let's say by June.”

Further Reading

If the new space companies can make this work—and what was once a big if continues to diminish in size as SpaceX and Blue Origin crash through reusability barriers—it could completely remake the economics of spaceflight. Launch costs are driven by hardware, not propellants. The cost to fuel a Falcon 9 rocket with liquid oxygen and kerosene propellant is about $200,000, Musk said. The company’s commercial launch price is $61 million.

Initially SpaceX plans to reduce the cost of a Falcon 9 rocket with a reused booster to $43 million per flight, a savings of 30 percent. But this is only the beginning. Musk wants to make nearly all of the Falcon 9 launch system reusable, and he wants to make launches and landings routine. “Rapid and complete reusability is really important to make a rocket cost effective, like an airplane,” he said. “We've got to ultimately get rockets to that point.” A Falcon 9 might fly as many as 100 times before retirement, he added.

For now, however, Musk and SpaceX are living in the moment. He said the company’s senior engineers believed there was about a two-in-three chance of nailing Friday’s landing. Though the company failed five previous times to make a soft, successful barge landing, they learned from those mistakes, and they fixed those problems. But there are always unknown unknowns in spaceflight. So when the moment came Friday, and the rocket stuck, Musk was ecstatic. He could hardly say what would come next. “We're a little bit like the dog who caught the bus,” Musk said, smiling. “What do we do now?”

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